Chymotrypsin pancreatic

Bovine pancreatic chymotrypsin (Mr 25,191) is a protease, an enzyme that catalyzes the hydrolytic cleavage of peptide bonds. This protease is specific for peptide bonds adjacent to aromatic amino acid residues (Trp, Phe, Tyr). The three-dimensional structure of chymotrypsin is shown in Figure 6-18, with functional groups in the active site emphasized. The reaction catalyzed by this enzyme illustrates the principle of transition-state stabilization and also provides a classic example of general acid-base catalysis and covalent catalysis. 

Recently the effects of alcalase (another protease from subtilisin family), bovine pancreatic chymotrypsin, and papain (from papaya) have been evaluated on the desquamatory process.45 Alcalase (or Optimase) is an alkaline serine proteases derived from Bacillus licheniformis with... 

FIGURE 17.10 Effect of bovine pancreatic chymotrypsin on visual scaling after a 3 h occluded application. Vehicle (square), 0.5% chymotrypsin (diamonds), heat inactivated chymotrypsin (triangles). P < 0.05. From El-Kadi, K., Rawlings, A.V., Feinberg, C., Nunn, C., Battaglia, A., Chandar, R, Richardson, N., Sabin, R., and Pocalyko, D. Arch. Dermatol. Res., 293, 500-507, 2001. 

One goal in the design of an inhibitor is specificity. Often this is a considerable challenge since physiological systems contain a number of closely related proteases. For example, there are at least four chymo-trypsin-like enzymes in humans. These include pancreatic chymotrypsin, cathepsin G, and two mast cell proteases (the human enzymes have not been characterized yet, but two are found in rats). All of these enzymes... 

The enzymatic digestion of the purified proteins was carried out as described (13). The enzymes TPCK-treated pancreatic trypsin (EC 3.4.21.4 Type XIII) and TLCK-treated pancreatic chymotrypsin (EC 3.4.21 Type VII) were from Sigma Chemical Company. The amount of proteinase used was 2% of the concentration of the purified protein. The proteins were dissolved in 200 oL of 0.1 N ammonium bicarbonate buffer (pH=7.0), followed by addition of the enzyme dissolved in deionized water. The enzymatic digestion was carried out by incubating the samples for 18 hours at 37° and the reaction was stopped by addition of 10% trifluoroacetic acid solution. The proteins were lyophilized. 

Benzamide known as benti romide, is a chymotrypsin substrate of value as a diagnostic acid for assessment of pancreatic function. It is synthesized by amide formation between... 

There are two main classes of proteolytic digestive enzymes (proteases), with different specificities for the amino acids forming the peptide bond to be hydrolyzed. Endopeptidases hydrolyze peptide bonds between specific amino acids throughout the molecule. They are the first enzymes to act, yielding a larger number of smaller fragments, eg, pepsin in the gastric juice and trypsin, chymotrypsin, and elastase secreted into the small intestine by the pancreas. Exopeptidases catalyze the hydrolysis of peptide bonds, one at a time, fi"om the ends of polypeptides. Carboxypeptidases, secreted in the pancreatic juice, release amino acids from rhe free carboxyl terminal, and aminopeptidases, secreted by the intestinal mucosal cells, release amino acids from the amino terminal. Dipeptides, which are not substrates for exopeptidases, are hydrolyzed in the brush border of intestinal mucosal cells by dipeptidases. 

Some of the pancreatic enzymes in the lumen include pancreatic amylase, pancreatic lipase, elastase, trypsin, a-chymotrypsin, and carboxypeptidase A. For example, the aspirin derivatives aspirin phenylalanine ethyl ester, aspirin phenyllactic ethyl ester, and aspirin phenylalanine amide have been studied as substrates for carboxypeptidase A [67,68], with the phenylalanine ethyl ester derivative proving to be the best substrate. This study indicated that the carboxypeptidase A may serve as a reconversion site for many drug derivatives. 

Chymotrypsin has also been utilized to promote debridement, as well as the reduction of soft tissue inflammation. It is also used in some opthalmic procedures, particularly in facilitating cataract extraction. It is prepared by activation of its zymogen, chymotrypsinogen, which is extracted from bovine pancreatic tissue. 

Besides the formation of luminescent silver clusters in fixed cells, likely due to the presence of proteins, fluorescent silver clusters have been synthesized using proteins as templates. In 2008, Pal et al. reported on the use of an enzyme, bovine pancreatic a-chymotrypsin (CHT) as biotemplate during the chemical reduction of... 

A few other helical conformations occur occasionally in globular protein structures. The polyproline helix, of the same sort as one strand out of a collagen structure, has been found in pancreatic trypsin inhibitor (Huber et al., 1971) and in cytochrome c551 (Almassy and Dickerson, 1978). An extended e helix has been described as occurring in chymotrypsin (Srinivasan et al., 1976). In view of the usual variability and irregularity seen in local protein conformation it is unclear that either of these last two helix types is reliably distinguishable from simply an isolated extended strand however, the presence of prolines can justify the designation of polyproline helix. 

The process for sheepskin is rather more gentle in order to avoid damage to top quiity wool that can be spun into valuable wool yarn. Liquid protease preparations such as pancreatic extracts of trypsin and chymotrypsin are applied to the flesh side of the sheepskin. The proteases diffuse to the basal papilla of the hair follicle, and subsequent protein breakdown releases the wool hair with minimal damage 34),... 

For example, chymotrypsin cleaves peptides on the C-terminal side of aromatic amino acid residues phenylalanine, tyrosine, and tryptophan, and to a lesser extent some other residues with bulky side-chains, e.g. Leu, Met, Asn, Gin. On the other hand, trypsin cleaves peptides on the C-terminal side of the basic residues arginine and lysine. Elastase usually catalyses hydrolysis of peptide bonds on the C-terminal side of neutral aliphatic amino acids, especially glycine or alanine. These three pancreatic enzymes are about 40% identical in their amino acid sequences, and their catalytic mechanisms are nearly identical. 

V. Schellenberger, U. Schellenberger, Y.V. Mitin, H.D. Jakubke, Characterization of the S -subsite specificity of bovine pancreatic a-chymotrypsin via acyi transfer to added nucieophiles, Eur. J. Biochem. 187(1) (1990) 163-167. 

Asafetida, administered orally to albino rats at a dose of 250 mg% for 8 weeks, enhanced pancreatic lipase activity, stimulated pancreatic amylase and chymotrypsin. The stimulatory influence was not observed when their intake was restricted to a single oral dose " " ". Protein digestibility. Asafetida did not affect the digestibility of protein in sorghum " . ... 

Minkowski tried unsuccessfully to prepare an extract of dog pancreas that would reverse the effect of removing the pancreas—that is, would lower the urinary or blood glucose levels. We now know that insulin is a protein, and that the pancreas is very rich in proteases (trypsin and chymotrypsin), normally released directly into the small intestine to aid in digestion. These proteases doubtless degraded the insulin in the pancreatic extracts in Minkowski s experiments. 

Thiosulfate cyanide sulfurtransferase symmetry in 78 TTiiouridine 234 Three-dimensional structures of aconitase 689 adenylate kinase 655 aldehyde oxido-reductase 891 D-amino acid oxidase 791 a-amylase, pancreatic 607 aspartate aminotransferase 57,135 catalytic intermediates 752 aspartate carbamyltransferase 348 aspartate chemoreceptor 562 bacteriophage P22 66 cadherin 408 calmodulin 317 carbonic acid anhydrase I 679 carboxypeptidase A 64 catalase 853 cholera toxin 333, 546 chymotrypsin 611 citrate synthase 702, 703 cutinase 134 cyclosporin 488 cytochrome c 847 cytochrome c peroxidase 849 dihydrofolate reductase 807 DNA 214, 223,228,229, 241 DNA complex... 

The mammalian serine proteases have a common tertiary structure as well as a common function. The enzymes are so called because they have a uniquely reactive serine residue that reacts irreversibly with organophosphates such as diisopropyl fluorophosphate. The major pancreatic enzymes—trypsin, chymotrypsin, and elastase—are kinetically very similar, catalyzing the hydrolysis of peptides... 

The mammalian serine proteases appear to represent a classic case of divergent evolution. All were presumably derived from a common ancestral serine protease.23 Proteins derived from a common ancestor are said to be homologous. Some nonmammalian serine proteases are 20 to 50% identical in sequence with their mammalian counterparts. The crystal structure of the elastase-like protease from Streptomyces griseus has two-thirds of the residues in a conformation similar to those in the mammalian enzymes, despite having only 186 amino acids in its sequence, compared with 245 in a-chymotrypsin. The bacterial enzymes and the pancreatic ones have probably evolved from a common precursor. 

Abbreviations MBN, myoglobin MGN, myogen MHN, myohemerythrin RUB, mbredoxin ICG, immunoglobulin constant region IGV, immunoglobulin variable region PBN, prealbumin SDM, superoxide dismutase CON, conconavalin A CHT, chymotrypsin INS, insulin PTI, pancreatic trypsin inhibitor CB5, cytochrome b5 ... 

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